Visible-spark plug



A. T. CRANE.

VISIBLE SPARK PLUG.

APPLICATION FILED JUNE 24,1920.

Patented Aug. 15, 1922 I: v I; Q? 1o 2 Q /5 5 I l 55 narrate staresearan r ease.

ARTHUR T. enema, or wernnnnny, cominc'rrcu'r, ssrenoaro THE CHASEcoivrranins Inc, or wnrnan'cnr, connncrrcnr, A CORPORATION.

I VISIBLE-SPARK rites;

Application filed June 24.,

To all whom it may 001mm.-

it known that I, ARTHUR T. CnANn,a citizen of the United States,residing at V Vaterbury, in the county of New Haven and State ofConnecticut, have invented a new and useful Improvement in Visible-SparkPlugs; and I do hereby declare the follouu ing, when taken in connectionwith the accompanying drawings and the characters of reference markedthereon, to be a full, clear, and exact description of the same, andwhich said drawings constitute part of this appli cation, and represent,in

Fig. l. A View partly in vertical section and partly in elevation of avisible spark plug embodying my invention.

Fig. 2. A detached View in side elevation of the terminal-cap.

Fig. 3. A reverse plan View thereof.

Fig. 4. A detached perspective view of the sparking-disk.

My invention relates to an improvement in visible spark-plugs, so-calledbecause constructed for the breaking of the current at the upper end ofthe plug for the production of a visible spark to enable the user totrace the current up to the spark-plug without resorting to any manualtests, the object of my present invention being to produce a simple,convenient and effective plug of the character described, constructedwith partic-.

' ular reference to its provision with a definite sparking-point ofpredetermined location, so that the spark-gap or distance between thesparking-point and the electrode may be accurately pre-gaged, as amanufacturing proposition, whereas in the visible sparlcplu 's of theprior art, no such point has been furnished and the spark has leapt fromthe nearest point in the cap to the electrode. A further object of myinvention is to provide a sparking-point of a material which will notbreak down and cause the deteriorationof the plug, preferably the samematerial as the electrode itself.

lVith these. ends in view, my invention consists in a visible spark-plugcharacterized by a spark-chamber having lateral openings and by asparking-member carried by the terminal-cap of the plug by which it isspaced apart from the core to assist in forming the spark-chamber andfurnishing a sparking-point in line with the electrode of the plug.

My invention further consists 111 certain- Specification of LettersPatent.

Patented Aug. 15,1922... 192s. eel-18.1 No. 391,294.

details of constructionas will behereinaften described and pointed outin the claims.

In carrying out myinvention, as herein shown, I employ a sparking memberconslsting, as shown, of a disk 2 centrally struck downward to form asparking-point 3 and having its edges-inserted into an annular bead aoffsetting from the upper corner of a cylindrical terminal-cap 5 setover an inte-.

gral annular shoulder 6 at the upper end of the insulating-core 7 of theplug'which may be of any approved construction and which, as showncomprises a shell 8 in which the pore is held by a deformable soft metalgas- ;et 9.

The said cap is formed at a. point'below its bead A with an inwardlystruck position- 'ing-knurl 10 which rests upon the upper edge of theshoulder 6, Whereby'the cap is positioned upon the core to which it is.firmly secured by spinning its edge inward under the lower edge ofthesaid shoulder to form the retaining-flange 11. Theknurl 10' aforesaid isformed with a plurality of round sight-holes or perforations 12 whichprovide for visualizing, as it were, upon the outside of the cap,theillumination of the interior or spark-chamber 13 thereof, bythesparking taking place when the current leaps from the sparking-point 3of the disk 2 to the electrode 1 L which traversesthe center of the core7 and projects a trifle above the center of the face of the upper end ofthe core, as shown in Fig. 1. The cap is formed with an externallythreaded hollow stem 15 for the reception of the usual binding nut 16.By preference, the sparking-disk 2 will. be made of nickel manganese ofthe same. composition as that used in the electrode 14:, though this isnot essential. I .donot limit myself to the use of nickel manganeseeither for the electrode or for the disk, but when Under ahled topredetei'lnine the distance of the disk from the electrode in theassembled device. On the other hand, in the spark-plugs ot the priorart, the spark leapt from the nearest point in the cap to the electrode,the point selected by the current being dependent upon the indii 'idualvariations present in any given plug.

I claim: 1. A. visible sparleplug having a shell, an insulating core,an. electrode therein, a terminal-cap positioned upon the core toproduce a sparlachainber which is pierced by lateral sigg'ht-ogenings,and a sparkingdisk mounted by its edge in the said cap at a point abovethe said sight-openings and furnishing a sparking-pointin line with thesaid electrode.

2. A visible spark-plug having a shell, an insulating core, an electrodetherein, a terminal-cap positioned upon the core to pro sis-reams duce aspark-chamber which is pierced by lateral sighhopenings, and asparking-disk mounted by its edge in the said cap at a pointabove thesaid sight-openings and struck downward to term a sparking-point locatcdin line with the said electrode.

A Visible spark-plug having-a shell, an insulating core, an electrode, aterminalcap mounted upon the core and "formed with an annular bead andwith lateral sightholes located between the head and the core, and asparking-disk mounted in the said head by which it is spaced apart fromthe core with; its center in line with the electrode.

In testimony whereof, I have signed this specification in the presenceof two subscribing witnesses. I

. ARTHUR- T. CRANE. Witnesses I JOHN S. NEAGLE, F. W. BROVVNM

